The purpose of this project is to study the regulation of the globin genes at the molecular level. The approach is to identify regulatory factors which influence globin gene expression. Evidence has been obtained for the existence of a positive regulatory factor(s) in induced 2S mouse erythroleukemia cells which can turn on the human fibroblast globin genes in MEL x human fibroblast hybrids. Attempts are being made to isolate, purify and characterize these factors using the technique of physical microinjection.